Kiosks are a good place for tablets (touch screens) because there is usually no desk, they are not typically used for extended periods of time (tireness), and many people that don't know how to use computers use them.*
So are phones (due to the form factor, and people don't usually use a phone on a desk).
But for a desktop? Most/all of the benefits of touchscreen don't apply. It just looks silly.
If it's a desktop for toddlers or old people, I can understand. But if you are going to use it for longer periods of time, might as well learn to use the mouse.
*I agree touchscreens can be more intuitive and easy to learn, but with some training, the mouse is much more effective.